Magnetic head feeding device with a rack and pinion

Abstract

A magnetic head feeding device suitable for mass production while providing a higher tolerance to vibration and shock is provided. A carriage is rotatably and slideably mounted on a guide shaft. A magnetic head is mounted on the carriage as is a rack. A pinion mounted on a motor, engages the rack to move the rack along the guide shaft in a reciprocating fashion when the pinion is rotated. A magnetic coupling between the carriage and a fixed support provides an attractive force which acts as an engagement force between the rack and the pinion without applying a contact force on the carriage. A stop is provided at each end of the rack and is integrally formed with the rack so that the stop prevents the pinion from rotating and the carriage from moving once the carriage has reached a desired outer limit of motion in either direction. A contour wall is integrally formed with the rack at a position opposed to the rack to prevent disengagement of the pinion from the rack.

What is claimed is: 
     
       1. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack member formed with an opening for defining a rack mounted on the carriage and extending essentially parallel to the direction along the guide, the rack member including stop means and disengagement prevention means integrally formed in the rack member;   a pinion means engaged with the rack for moving the carriage along the guide when the pinion means is rotated;   motor means for rotating the pinion means in a reciprocating manner; and   an output shaft rotated by the motor means, the pinion means being mounted on the output shaft;   the stop means controlling the rotation of the pinion means and the movement of the carriage and comprising the opening formed in the rack, a first side wall and an opposed second side wall at the respective ends of the rack to stop rotation of the pinion means at the ends of the rack, and the disengagement prevention means preventing disengagement of the rack from the pinion means and including a disengagement wall opposite and spaced from the rack, the distance between the disengagement wall and the rack being slightly greater than the dimension of the pinion means.   
     
     
       2. The magnetic head feeding device of claim 1, wherein the stop means is in registration with the pinion means, the stop means including a projection formed on at least one of the side walls, the projection being formed adjacent the end of the rack for engagement by the pinion means to stop the rotation of the pinion means and displacement of the carriage. 
     
     
       3. The magnetic head feeding device of claim 1, the stop means including a wall facing and spaced from the rack in registration with the pinion means at least in the region adjacent to at least one of the side wall, the rotation of the pinion means being stopped by engagement of the pinion means with the rack and facing wall. 
     
     
       4. The magnetic head feeding device of claim 1, adapted for use with a recording medium, further comprising a plurality of teeth integrally formed on the rack, the pitch of the teeth being less than twice the track pitch of the recording medium. 
     
     
       5. The magnetic head feeding device of claim 1, adapted for use with a recording medium having a diameter no less than 4 inches, wherein the diameter of the output shaft is no more than 2.1 millimeters. 
     
     
       6. The magnetic head feeding device of claim 1, adapted for use with a recording medium and wherein said pinion means includes a pinion mounted on the output shaft, the diameter of the output shaft being no more than 1.6 millimeters and the recording medium is a disc, the disc diameter being no more than 4 inches. 
     
     
       7. The magnetic head feeding device of claim 1, further comprising a spacer mounted on the carriage, the magnetic head being mounted on a non-magnetic spacer, the carriage being formed with a rim about the periphery of the magnetic head the carriage being formed of a material having a high permeance at least in the region beneath the magnetic head and in said rim, thereby shielding the magnetic head from outside magnetic leaks. 
     
     
       8. The magnetic head feeding device of claim 7, for use with a magnetic medium, the magnetic head having a head core, and including an annular magnetic shield member supported so as to extend about the head core of the magnetic head, the annular magnetic shield member being formed of a material of high permeance and essentially lying in a plane extending parallel to the magnetic medium. 
     
     
       9. The magnetic head feeding device of claim 1, wherein said rack, said stop means and said disengagement prevention means are integrally formed as a plate member affixed to said carriage. 
     
     
       10. The magnetic head feeding device of claim 9, wherein said plate member is integrally formed with said carriage. 
     
     
       11. The magnetic head feeding device of claim 1, wherein the pinion means includes a pinion mounted on the output shaft, the disengagement wall is a contour wall supported opposite and spaced from the rack for displacement with the rack as a unit, the contour wall being in registration with at least one of the output shaft and pinion, the distance between the contour wall and the rack being slightly greater than one of the diameter of the pinon or output shaft whereby the pinon is able to rotate along the rack and remain in contact with the rack, the contour wall limiting the displacement of the pinion in a direction to disengage the pinion from the rack. 
     
     
       12. The magnetic head feeding device of claim 11, wherein the surface of the first side wall and the second side wall is formed as an arc having a diameter larger than the diameter of the pinion. 
     
     
       13. The magnetic head feeding device of claim 12, wherein the stop means is in registration with the pinion, the pinion engaging either the first side wall or the second side wall and rack to stop the rotation of the pinion and displacement of the carriage. 
     
     
       14. The magnetic head feeding device of claim 1, further comprising control means for controlling the position of the magnetic head. 
     
     
       15. The magnetic head feeding device of claim 14, wherein the output shaft carries the pinion means, and the control; means includes the motor means having an output portion rotatable concentrically with the shaft for positioning the magnetic head; and means for securing the outer portion of the motor means from rotation during operation. 
     
     
       16. The magnetic feeding device of claim 14, wherein the control means includes an adjustable movement means for selectively displacing the motor means in the direction of reciprocating movement of the carriage. 
     
     
       17. The magnetic head feeding device of claim 1, wherein said pinion means is a pinion and said output shaft is a motor shaft. 
     
     
       18. A magnetic head feeding device of claim 17, wherein the outer surface of the pinon forms teeth, the motor means is a step motor and the number of pinion teeth is at least one half the step number of one rotation of the step motor. 
     
     
       19. The magnetic head feeding device of claim 17, wherein the surface of the first side wall and the second side wall is formed as an arc having a diameter larger than the diameter of the pinion. 
     
     
       20. The magnetic head feeding device of claim 19, wherein the stop means is in registration with the pinion means, the pinion means engaging either of first side wall or second side wall and rack to stop the rotation of the pinion and displacement of the carriage. 
     
     
       21. The magnetic head feeding device of claim 1, further comprising pressure imparting means for imparting an engagement force between the rack and pinion means without contacting the carriage. 
     
     
       22. The magnetic head feeding device of claim 21, wherein the pressure imparting means includes magnet means for imparting said engagement force by either magnetic attraction or magnetic repulsion. 
     
     
       23. The magnetic head feeding device of claim 21, wherein the pressure imparting means comprises a fixed support; and a magnet supported on one of the carriage and the fixed support and positioned on the same side of the guide as the rack, at least the portion of the other of the fixed support and carriage in registration with the magnet being made of a material attracted by the magnet, the magnet and magnetically attracted material not coming in contact with each other. 
     
     
       24. The magnetic head feeding device of claim 21, wherein the pressure imparting means comprises a fixed support; a first magnetic means supported on one of the carriage and the fixed support and positioned on the opposite side of the guide as the rack; and a second magnetic means selected for magnetic repulsion to said first magnetic means supported on the other of the carriage and the fixed support in registration with the first magnetic means during the sliding displacement of the carriage, the first and second magnetic means not coming in contact with each other. 
     
     
       25. The magnetic head feeding device of claim 21, adapted for use with a recording medium, further comprising a plurality of teeth integrally formed on the rack, the pitch of the teeth being less than twice the track pitch of the recording medium. 
     
     
       26. A magnetic head feeding device of claim 21, wherein the pinion means includes a pinion and the outer surface of the pinion forms teeth, the motor means is a step motor and the number of pinion teeth is at least one half the step number of one rotation of the step motor. 
     
     
       27. The magnetic head feeding device of claim 21, adapted for use with a recording medium having a diameter no less than 4 inches, wherein the diameter of the output shaft is no more than 2.1 millimeters. 
     
     
       28. The magnetic head feeding device of claim 21, adapted for use with a recording medium and wherein said pinion means includes a pinion mounted on the output shaft and the recording medium is a disc, the diameter of the output shaft being no more than 1.6 millimeters and the disc diameter being no more than 4 inches. 
     
     
       29. The magnetic head feeding device of claim 21, further comprising a spacer mounted on the carriage, the magnetic head being mounted on a non-magnetic spacer, the carriage being formed with a rim about the periphery of the magnetic head the carriage being formed of a material having a high permeance at least in the region beneath the magnetic head and in said rim, thereby shielding the magnetic head from outside magnetic leaks. 
     
     
       30. The magnetic head feeding device of claim 21, for use with a magnetic medium, the magnetic head having a head core, and including an annular magnetic shield member supported so as to extend about the head core of the magnetic head, the annular magnetic shield member being formed of a material of high permeance and essentially lying in a plane extending parallel to the magnetic medium. 
     
     
       31. The magnetic head feeding device of claim 21, wherein the rack is formed separate from the carriage and joined thereto. 
     
     
       32. The magnetic head feeding device of claim 31, wherein the coupling of the rack to said carriage permits independent thermal dimensional changes of the carriage and rack, the material of the rack being selected to compensate for differences in thermal dimensional changes between the carriage and the medium used with the device. 
     
     
       33. The magnetic head feeding device of claim 21, wherein said pinion means includes a pinion, the output shaft carrying the pinion, the disengagement wall is a contour wall supported opposite and spaced from the rack for displacement with the rack as a unit, the contour wall being in registration with either the output shaft or pinion, the distance between the contour wall and the rack member being slightly greater than one of the diameter of the pinion or output shaft whereby the pinion is able to rotate along the rack and remain in contact with the rack, the contour wall limiting the displacement of the pinion in a direction to disengage the pinion from the rack. 
     
     
       34. The magnetic head feeding device of claim 33, wherein the stop means is in registration with the pinion, the stop means including a projection formed on at least one of the side walls, the projection being formed adjacent the end of the rack member for engagement by the pinion to stop the rotation of the pinion and displacement of the carriage. 
     
     
       35. The magnetic head feeding device of claim 33, the contour wall being in registration with the pinion and the rotation of the pinion being stopped by engagement of the pinion with the contour wall and rack. 
     
     
       36. The magnetic head feeding device of claim 33, wherein the surface of the first side wall and the second side wall is formed as an arc having a diameter larger than the diameter of the pinion. 
     
     
       37. The magnetic head feeding device of claim 36, wherein the stop means is in registration with the pinion, the pinion engaging either the first side wall or the second side wall and rack to stop the rotation of the pinion and displacement of the carriage. 
     
     
       38. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack mounted on the carriage and extending essentially parallel to the direction along the guide;   a pinion engaged with the rack for moving the carriage along the guide when the pinion is rotated;   motor means for rotating the pinion in a reciprocating manner;   pressure imparting means for imparting an engagement force between the rack and the pinion without contacting the carriage;   stop means for preventing further movement of the carriage in a selected direction; and   disengagement prevention means for preventing disengagement of the rack from the pinion, wherein the rack, the stop means and the disengagement prevention means are integrally formed with the carriage.   
     
     
       39. The magnetic head feeding device of claim 38, wherein the pressure imparting means includes magnet means for imparting said engagement force by either magnetic attraction or magnetic repulsion. 
     
     
       40. The magnetic head feeding device of claim 38, wherein the pressure imparting means comprises a fixed support; and a magnet supported on one of the carriage and fixed support and positioned on the same side of the guide as the rack, at least the portion of the other of the fixed support and carriage in registration with the magnet being made of a material attracted by the magnet, the magnet and magnetically attracted material not coming in contact with each other. 
     
     
       41. The magnetic head feeding device of claim 38, wherein the pressure imparting means comprises a fixed support; a first magnetic means supported on one of the carriage and the fixed support and positioned on the opposite side of the guide as the rack; and a second magnetic means selected for magnetic repulsion to said first magnetic means supported on the other of the carriage and the fixed sliding displacement of the carriage; the first and second magnetic means not coming in contact with each other. 
     
     
       42. The magnetic head feeding device of claim 38, including an output shaft rotated by the motor means and carrying the pinion, the disengagement prevention means comprising a contour wall support opposite and spaced from the rack for displacement with the rack as a unit, the contour wall being in registration with at least one of the output shaft and pinion, the distance between the contour wall and the rack being slightly greater than on of the diameter of the pinion or output shaft whereby the pinion is able to rotate along the rack and remain in contact with the rack, the contour wall limiting the displacement of the pinion in a direction to disengage the pinion from the rack. 
     
     
       43. The magnetic head feeding device of claim 38, further comprising control means for controlling the position of the magnetic head. 
     
     
       44. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack mounted on the carriage and extending essentially parallel to the direction along the guide;   a pinion engaged with the rack for moving the carriage along the guide when the pinion is rotated;   motor means for rotating the pinion in a reciprocating manner;   stop means for stopping movement of the carriage in a selected direction; and   disengagement prevention means for preventing disengagement of the rack from the pinion, wherein the rack, the stop means and the disengagement prevention means are integrally formed with the carriage as a unitary rack member.   
     
     
       45. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack mounted on the carriage and extending essentially parallel to the direction along the guide;   a pinion engaged with the rack for moving the carriage along the guide when the pinion is rotated;   motor means for rotating the pinion in a reciprocating manner;   stop means for stopping movement of the carriage in a selected direction;   disengagement prevention means for preventing disengagement of the rack from the pinion, wherein the rack, the stop means and the disengagement prevention means are integrally formed with the carriage as a unitary rack member; and   an output shaft rotated by the motor means and carrying the pinion, the disengagement prevention means comprising a contour wall supported opposite and spaced from the rack for displacement with the rack as a unit, the contour wall being in registration with either the output shaft or pinion, the distance between the contour wall and the rack being slightly greater than one of the diameter of the pinion or output shaft whereby the pinion is able to rotate along the rack and remain in contact with the rack, the contour wall limiting the displacement of the pinion in a direction to disengage the pinion from the rack.   
     
     
       46. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack mounted on the carriage and extending essentially parallel to the direction along the guide;   a pinion engaged with the rack for moving the carriage along the guide when the pinion is rotated;   motor means for rotating the pinion in a reciprocating manner;   stop means for stopping movement of the carriage in a selected direction; and   disengagement prevention means for preventing disengagement of the rack from the pinion, wherein the rack, the stop means and the disengagement prevention means are integrally formed with the carriage as a unitary rack member;   and pressure imparting means for imparting an engagement force between the rack and pinion without contacting the carriage.   
     
     
       47. The magnetic head feeding device of claim 46, wherein the pressure imparting means includes magnet means for imparting said engagement force by either magnetic attraction or magnetic repulsion. 
     
     
       48. The magnetic head feeding device of claim 46, wherein the pressure imparting means comprises a fixed support; and a magnet supported on one of the carriage and fixed support and positioned on the same side of the guide as the rack, at least the portion of the other of the fixed support and carriage in registration with the magnet being made of a material attracted by the magnet, the magnet and magnetically attracted material not coming in contact with each other. 
     
     
       49. The magnetic head feeding device of claim 46, wherein the pressure imparting means comprises a fixed support; a first magnetic means supported on one of the carriage and the fixed support and positioned on the opposite side of the guide as the rack; and a second magnetic means selected for magnetic repulsion to said first magnetic means supported on the other of the carriage and the fixed support in registration with the first magnetic means during the sliding displacement of the carriage, the first and second magnetic means not coming in contact with each other. 
     
     
       50. A magnetic head feeding device comprising: a guide;   a carriage slideably and rotatably mounted on the guide, the carriage being reciprocally moveable in a direction along the guide;   a magnetic head mounted on the carriage;   a rack mounted on the carriage and extending essentially parallel to the direction along the guide;   a pinion engaged with the rack for moving the carriage along the guide when the pinion is rotated;   motor means for rotating the pinion in a reciprocating manner;   stop means for stopping the carriage from travelling in a selected direction;   disengagement prevention means for preventing disengagement of the rack from the pinion; and   control means for controlling the position of the magnetic head, wherein the rack, the stop means and the disengagement prevention means are integrally formed with the carriage as a unitary rack member.   
     
     
       51. The magnetic head feeding device of claim 50, and including an output shaft rotated by the motor means and carrying the pinion, the control means comprising the motor means having an output portion rotatable concentrically with the shaft for positioning the magnetic head; and means for securing the outer portion of the motor means from rotation during operation. 
     
     
       52. The magnetic feeding device of claim 50, wherein the control means includes an adjustable movement means for selectively displacing the motor means in the direction of reciprocating movement of the carriage.